Repeating alarm timer



June 20, 1939. H WARREN 2,163,419

REPEATING ALARM TIMER Filed Sept. 29, 1937 Fig. l.

Insular! Inventor: Henry E. Warren,

9 His Attorney.

Patented June 20, 1939 PATENT OFFICE REPEATING ALARM TIMER Henry E.Warren, Ashland, Mass assignor to Warren Telechron Company, Ashland,Mass., a corporation of Massachusetts Application September 29, 1937,Serial No. 166,368

7 Claims.

My invention relates to timing devices of the type which is intended toproduce an alarm or other signal at the end of a predetermined andpreferably adjustable period of time subsequent to setting the timerinto operation or to time other events, to count the number ofrevolutions of a motor, etc. Such a device is useful for example fortiming processes and to notify an attendant when the time forcompleting: certain process has expired.

In carrying my invention into effect, I preferably employ a constantspeed alternating current motor as the timing element of the device andutilize the alternating flux of the motor for sounding an alarm at theexpiration of the time The features of my invention which are believedto be novel and patentable will be pointed out in the claims appendedhereto. For a better understanding of my invention, reference is made inthe following description to the accompanying drawing in which Fig. 1shows a perspective exploded view of the essential parts of a repeatingalarm timer constructed in accordance with the present invention; andFig. 2 represents a modified form of timer arranged to sound acontinuous alarm at the end of the timing interval.

Referring to Fig. 1, I0 represents the stator of a self-startingsynchronous timer motor, the rotor of which together with suitablereduction gearing is contained in the barrel II and from which a timeroperating shaft I2, driven by the motonextends. Shaft I2 carries a gearI3 which may mesh with a gear I4 secured on a shaft I5. Shaft I5 isrotatively mounted in a bearing IE on a framework I1. Framework I1 issecured to the near end of a shaft I8 pivoted on its own axis insupporting structure not shown. Shaft I8 is of resilient material andhas some torsional spring action and has secured to it, adjacent its farend, a magnetic bar 20, which comprises an armature with respect to polepieces 21 and 22 projecting from the motor stator on opposite sides ofthe motor energizing winding 23. A spring I9 is provided which tends torotate shaft I8 in a counterclockwise direction, retracting armature 28away from its pole pieces and moving gear I4 to the right and out ofmesh with gear I3. The axes of rotation of gears I3, I4 and frame I1 areparallel. Rotary motion of shaft I8 and the parts attached thereto islimited by a stop such as the stop pin 24.

pointer 28 is a time setting dial 32. normally stationary, it being heldagainst rota- When the motor is energized from a suitable source ofalternating current, designated at 48, the major portion of its fluxtraverses the rotary armature air gap and shaft I2 is driven at aconstant speed. A certain amount of leakage flux 5 tends to crossthrough armature 20 between pole pieces 2| and 22 and the armature isattracted into contact with such pole pieces rotating shaft I8 clockwiseand swinging shaft I5 slightly to the left of the position shown, andengaging gears 10 I3 and I4 in driving relation.

When the motor is deenergized the armature 20 is retracted as shown andthe frame I'1 rests against stop 24 due to the action of spring IS, withgears I3 and I4 disengaged. As thus far 5 described, then, the motorperforms two functions, as follows: It serves to drive gear I3 at aconstant speed when the motor is energized, and it serves to engage anddisengage gears I3 and I4 to and from driving relation as the motor isenergo gized and deenergized.

Gear I4 is on a shaft with a gear 25 which meshes at all times indriving relation with a gear 26. Gear 26 is secured to a time settingshaft 21 which carries a pointer indicator 28 on 25 its front end and acollar 29 on its rear end. A spring 38 is provided for returning timesetting shaft 21 counter-clockwise to an initial position when gears I3and I4 are completely disengaged. Spring 30 is secured between collar 2930 and some stationary structureso as to be wound up when shaft 21 isrotated in a clockwise direction by motor I0. It then serves to returnthe shaft 21 together with pointer 28, counterclockwise, to an initialpoistion as soon as the motor 5 is deenergized, to disengage the clutchcomprising gears I3 and I4. The initial position of shaft 21 isdetermined by a stop finger 3| projecting from the side periphery ofgear 26 and which is rotated by spring 30 into engagement 40 with pinion25 as a stop when gear I4 is disengaged from driving relation with gearI3. This initial position of time setting shaft 21 is then when stopfinger 3| rests against pinion 25, and preferably ,wlih pointer 28 ispointing straight 5 up.

Concentric with shaft 21 and cooperating with Dial 32 is tion byfriction. For this purpose the dial is 50 secured to a hollow shaft 33,carrying collars 34 and 31 on opposite sides of a plate 35 comprisingone of the stationary supporting plates of the device. A resilientfriction clutch member 36 is pressed between plate 35 and collar 31 withsufficient force to hold shaft 33 and dial 32 from rotation except whendial 32 is manually turned in an adjusting operation. For convenience inmanually adjusting dial plate 32 it is made in the form of a gear wheeland meshes with a small gear 38 which is provided with a knurled thumbpiece 33 for rotating the same.

The dial plate 32 is provided with a stop for pointer 28. In thisinstance I have shown the stop as including a contact device, althoughthe contact feature may be omitted. The actual stop comprises a pin 40of insulating material protruding from the side of dial 32 in the pathof rotation of pointer-28. However, in front of stop pin 40 I haveprovided a pair of normally open resilient contact fingers 4| and 42secured to the side of dial 32 at 43. These contact fingers are soarranged in the path of pointer 28 as it approaches stop pin 40 thattheir contact points will be pressed together as the finger 28 reachesstopping position. This contact device is illustrated as for the purposeof closing the circuit 44 of a relay 45 which may be utilized for anyclesired purpose, such, for example, as the stopping of a processoperation being timed by the timer mechanism.

The stopping positionof pointer 28 as determined by stop 40 ispreferably opposite the zero graduation mark on dial 32 and the dial isgraduated from this point in a counterclockwise di'- rection withsuitable time indications, such as seconds, minutes or hours, dependingupon what time range is desired and the rate at which the pointer 28 isnormally driven by the timing motor II'I. For the purpose of the presentillustration it may be assumed that the dial is graduated in minutes andthat if the dial is set so that pointer 28, when in its initial orup-right posi tion, is opposite I on the dial, it will require I5minutes for the pointer 28 to be driven to the zero mark and stoppingpoint. It is important that when pointer 28 comes against stop 40 itwill be positively stopped and will not rotate dial 32 through frictionclutch 35, 36. 4

I make use of the stopping action of pointer 28 and the continueddriving action of motor II] at the end of a time cycle to cause thearmature 20 to produce a penetrating audible signal which is repeatedevery few seconds until motor I0 is deenergized. This audible signalingaction will occur at the end of a timing operation and will'be explainedwhen we come to that point in reviewing the manner of setting, operatingand resetting the device for normal use.

Let it be assumed that the timer is to be used in connection with thedevelopment of photograph negatives, that it is desirable to leave thephotograph negativw in the developing solution for minutes. The circuitof motor I0 is opened at a switch 46 which may, for sake of convenience,be located in the dark room. The timer mechanism may be located in thesame or some other room. The attendant first sets dial 32 for 15 minuteoperation by turning the dial by means of knob 39 until it reads 15minutes with respect to pointer 28. It should be observed that withmotor In deenergized gear I4 will be demeshed from gear I3 and spring 30will have rotated finger 3| against stop gear 25 so that pointer 28 willpoint straight up. The attendant then places his negatives'in thedeveloping solution and closes switch 46 and goes about some other work.When the motor is energized, armature is attracted to polepieces 2| and22, gear I4 is meshed with gear I3 and the motor starts into operation.

Pointer 28 is driven towards the zero graduation on dial 32 at such aconstant rate as to reach this. point in 15 minutes, stop finger isrotated away from gear and spring is wound up. The direction of rotationof the gears I3 and I4 during this timing cycle are as indicated byarrows. At the end of 15 minutes pointer 28 is stopped by stop whichblocks gears 26, 25 and I4 from further rotation. The driving action ofmotor I6 continues and gear I3 is rotated in such direction with respectto blocked gear I4 that frame I1 is forced to the right, rotatingresilient shaft I8 counterclockwise and forcing armature 20 away frompole pieces 2|, 22. The motor is still energized so that armature 2|)now starts to chatter under the influence of the flux pulsations tendingto draw it to the pole pieces and the opposing force tending to pull itaway. The resiliency of shaft I8 augments this chattering action. As thearmature is pulled further and further away the chattering becomeslouder and louder until gears I3 and I4 havemoved far.

enough out of mesh to allow gear I3 to slip one tooth. This momentarilyrelieves the pulling away effect on armature 20 and it is-drawn towardthe pole pieces. This action and the resulting audible noise cycle isrepeated over and over as the teeth of gear I3 slip by the teeth in gearI4. As a result of this action there occurs a series of shortpenetrating sound signals each having a rising inflection, each suchsignal lasting for a few seconds and being almost immediately repeated.This notifies the attendant and he proceeds to stop the developmentprocess and as soon as convenient, he deenergizes the motor I0. As soonas motor I0 is deenergized, magnetic pull on armature 20 is relieved andgear I4 swings to full demeshed position with respect to gear I3. Thedriving connection between the motor and indicator 28 is interrupted.Spring 30 now returns stop finger 3| against gear 25 and pointer 28 toinitial position and the device is ready for another timing operation.

The use of gear 25 as a stop for finger 3| is not considered to beessential but it is helpful in preventing any rebound action of frame I!which might tend to reengage gear I4 with gear I3. It will be noted thatthis stopping action of finger 3| against gear 25 is in a direction totend to disengage gears I3 and I4. It will be noted that I have shown ashading coil 41 about a portion of pole piece 22. This is desirable toreduce magnetic hum of armature 20 when motor III is energized and whenthe armature is not intended to chatter. During audible signal operatingmotor I0 continues to run at constant speed. The frequency at which theaudible signal will be repeated will depend upon the number of teeth ingear I3 and its rate of rotation. Generally, it will be desirable tohave this signal repeat itself every few seconds and to arrange thespeed of shaft I2 and the number of teeth in gear I3 accordingly. Ifshaft I2 runs at 1 R. P. M. and gear I3 has 20 teeth, the audible signalcycle will have a duration of three seconds. The gear ratio of the trainbeyond this point to shaft 21 will depend upon the time range desired ondial 32. It will be evident that the motor actuated audible signalingarrangement described may be' employed in any'motor driven gear trainwhere it becomes desirable for any reason to give such a signal when thedrive to a load through the gear train becomes blocked.

It will be seen that the arrangement is suchthat the entire operation ofthe timer is controlled by one simple switch such as the switch 46 inthe circuit of the timer motor, and that this switch may be placedanywhere in the motor energizing circuit either adjacent to or somedistance from the timer. Or, if more convenient, several such switchesmay be provided in series in the motor circuit so that the timeroperation may be started by closing one switch 46 and stopping theoperation by opening another switch 46 located in another room. Alltimer operations are performed in their proper sequence by the singletime motor'as thus controlled and include starting a timing operation byclosing the motor circuit, sounding a signal at the end of suchoperation, and, if desired, performing some additional controllingoperation through the relay circuit 44 controlled by contacts 4 I-42,and stopping the audible signal, opening control contacts 4 I 42, andresetting the entire device for a subsequent timing operation uponopening the motor circuit.

It should also be observed that the timing operation may be stopped andthe device reset at any time before pointer 28 reaches stop 40, shouldthat be desired, by simply opening the circuit of motor III, in whichcase armature 28 would not produce the audible signal. The normal timeroperating period may be increased or decreased within the time range ofdial 32 by rotary adjustment of such dial and such adjustment may bemade before setting the device into operation or duringits operation.The device may be used to perform a timing operation and automaticallyrepeat such operation by including the normally closed contacts of atime delay relay shown at 35a in the circuit of motor I0 and connectingthe coil of this relay in the circuit of contacts 4I42.

When the indicator 28 reaches stopping position.

the contacts are closed and relay 45a energized and the motor I0deenergized. The electromagnetic clutch interrupts the drivingconnection at gears I3I4, indicator 28 returns to its initial position,contacts 4I42 open and the motor is again energized and repeats itsoperation. The time delay of relay 45a may be such as to allow the alarmto sound as well as to allow the timer to reset. The device may be madeto start or stop or both start and stop in response to any event to betimed. For example, let us suppose that the switch 46 represents athermostat switch responsive to temperature in a steam sterilizer, inwhich case the timer. would respond to the closing and opening of thethermostat switch and would give the time during which the tempera turewas uninterruptedly maintained above that corresponding to the settingof the thermostat and would sound an alarm if such temperature wasmaintained longer than necessary and the timer would reset withoutsounding an alarm if the temperature was not maintained long enough.Other uninterrupted processes or events may be timed in an analogousmanner.-

Likewise, the device will be useful in many cases where the motor I0,instead of measuring time, measures speed or some other quantity, andthe alarm is sounded after a certain number of revolutions independentof time. Hence, I do not wish to limit my invention to using a constantspeed motor at II).

In Fig. 2 I have represented a modified form of imer employing severalof the features of the timer of Fig. 1. Those parts which are similar inthe two figures are indicated by like reference characters.

In Fig. 2 the clutch operating arrangement for shifting gear I4 out ofmesh with gear I3 has been modified slightly because in thismodification I do not depend upon the chattering action of armature 50to produce a noise directly by striking its pole pieces. Instead, Imount a resilient bell clapper 5| on armature 50 and cause the hammer ofthis clapper to strike a bell 52 when armature 58 is set into vibrationat the end of a time cycle. The outer end of armature 50 is connected toframe 53 by rod 54. Frame 53 is pivoted at 55 and is biased towards stop24 by spring 56. The lower swinging end of frame 53 rotatively supportsshaft I5. In this figure as in Fig. 1 the parts have been shownconsiderably 'spread apart and it will be understood that in actualconstruction, shaft I5 will be short and gears I4 and 25 will be closetogether and close to the bearing of shaft I5 in framework 53 so as tomake a practicable construction.

In Fig. 2 gear 26 is not fixed on shaft 21 but is connected theretothrough a friction clutch, a part of which is shown at 51. The dialplate 58 is fixed and has a fixed stop pin 59 for pointer 28. Theinitial position of pointer 28 is determined by a stop hand 60. Hand 60is rotatively adjustable with respect to plate 58 but remains in anyposition of adjustment by reason of a friction coupling 8| between itand plate 58. Hand 68 has a projection 62 which catches and stops hand28 when the latter returns to its initial position. against stop 62 whenreset at the end of a timing operation. The distance of stop hand 60from the stop pin 58 determines the time setting of the device.

The operation of this device is as follows. Stop hand 50 is set awayfrom stop pin 59, a distance corresponding to the time setting desired.Spring 30 will rotate pointer 58 counter-clockwise against stop 62, whengears I3 and I4 are disengaged in any position of the stop hand 60.Motor I0 is then energized, armature 50 is attracted, and the bellreceives one stroke of hammer 5|. Gear I4 is engaged in driving relationwith gear I3. The motor starts into operation simultaneously and pointer28 is driven from an initial position opposite hand 60, clockwisetowards stop pin 59. Clutch 5! does not slip during this part of thecycle, and hence shaft 21 winds up spring 30. When pointer 28 is stoppedat post 59 at the end of the time cycle, clutch 51 starts to slip andthe torque transmitted through gears I3 and I4 is accordingly materiallyincreased, which tends to swing frame 53 counterclockwise and movearmature 50 away from its pole pieces against the pulsating magneticattraction of the motor field. As a result, the bell clapper is vibratedand rings bell 52.

It is unnecessary that the gears I4 will move away from gear I3 far'enough to cause gear I3 to slip its teeth in order to cause a vigorousringing of the bell. Of course, the friction at 51 may be madesufficient to block gear I4, in which case gear I3 will move gear I4to'the right until the tooth in I3 slips by the adjacent teeth of gearI4 so as to periodically vary the outer limit of vibration of armature50. This will cause some pulsating change in the sound of the alarm, asin Fig. 1. If such operation is desired, the friction clutch at 51 wouldnot be essential.

When the motor I0 is deenergized, gear I4 is demeshed from gear l3 andthe spring 30 returns pointer 28 to starting position against stop 62 ofhand 60, wherever it may be set. This gear demeshing and pointerresetting action is desirable whether an alarm be included or not andsuch resetting operation may, of course, occur before pointer. 58reaches post 59, should that become desirable. The hand 60 and pointer28 are preferably painted different colors in order that an operator,who may wish to observe the device during its operation to see how muchtime is left during a timing operation, may more easily distinguish thepointer 28. Control contacts may be included on dial plate 58, as inFig.

1, if that is desired.

In accordance with the provisions of the patent statutes, I havedescribed the principle of operation of my invention, together with theapparatus which I now consider to represent the best embodiment thereof,but I desire to have it understood that the apparatus shown is onlyillustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An alarm timer, including a movable indicator, an alternating currentelectric motor, a driving connection including a pair of rotativelymounted intermeshed gears between said motor and indicator whereby thelatter may be driven forward to indicate the number of rotations of saidmotor, a support for one of said gears pivoted on an axis of rotationparallel to the axes of rotation of said gears, resilient means tendingto rotate said support to swing the gear carried thereby out of meshwith the other gear to interrupt said driving connection, a magneticarmature connected to said support and positioned to be attracted to theelectric motor when the latter is energized to move said support againstthe action of said resilient means to establish said driving connection,the direction of rotation of the gears by said motor when the indicatoris driven by the motor thereby also tending to rotate said support toswing the gear carried thereby out of mesh with the other gear, thislast mentioned tendency plus the tendency of said resilient means beinginsufiicient to overcome the attraction of said armature to interruptsaid driving connection when the motor is energized and the indicator isbeing normally driven, means between said gears and indicator forblocking further forward movement of the indicator after it has beendriven forward by a predetermined amount, said blocking action and thecontinued operation of said motor causing the torque between said gearsto increase by an amount suflicient to cause movement of the armatureaway from its attracted position and permit it to vibrate, said armaturecomprising a portion of an audible alarm which is operated by suchvibration until the motor is deenergized.

2. In combination, a device to be-driven in a given direction, analternating current motor, a driving connection between said device andmotor, said connection including apair of gears, one of which is bodilymovable from a position in driving relation with the other gear awaytherefrom to a position where said driving connection is interruptei.-the bodily movement of said gear from driving position to the inter- Vrupted position being in the same direction in which said bodily movablegear tends to move by the transmission of power through said gears fromthe motor to the driven device when the latter is driven in said givendirection, a pivoted support on which the bodily movable gear isrotatively mounted, a magnetic armature connected to said support andpositioned to be attracted to said motor when the latter is energized torotate said support and moveits bodily movable gear to driving position,resilient means tending to rotate said support and move its bodilymovable gear to the interrupted position, said parts being so adjustedthat when the motor is energized and the torque transmitted throughsaidgears is normal, the driving connection is maintained, and when thetorque transmitted through said gears is in excess of normal, thearmature is pulled away from the motor and is caused to vibrate andsound an alarm.

3. In combination, an alarm mechanism, a

device to be driven in a given direction, an alter nating current motor,a driving connection between said motor and device, including a pair oftoothed gears pivoted for rotation on parallel axes, a frame pivoted toswing about an axis parallel to the axis of rotation of said gears andsupporting one of said gears so as to move the same into and out of meshwith the other gear the direction of rotation of said gears being suchas to tend to move the frame supported gear out of mesh with the othergear when the motor is in operation and driving said device in saidgiven direction, resilient means also tending to swing said frame in thedirection to demesh said gears, said alarm mechanism including a pivotedmagnetic armature which is attracted to the motor when the latter isenergized, a torsionally resilient shaft on which said armature andframe are both secured in spaced relation, the adjustment being suchthat when the motor is energised and the armature is attracted thereto,the gears are meshed in driving relation against the tendency of saidresilient means and the normal driving action of said gears to move themapart and when the driving connection on the driven side of said gearsis blocked, the motor continues to operate and moves said gears apartuntil their teeth slip with respect to each other, such slipping actionof the gears being accompanied by a variable movement of the armatureaway from attracted position and intense vibration thereof productive ofan audible sound which varies in intensity in cyclic relation to theslipping action of the gear teeth.

4. An alarm timer, comprising a time graduated dial, an indicatormovable with respect to said dial, a synchronous motor, a drivingconnection between said motor and indicator whereby the indicator may bedriven with respect to said dial to indicate the passage of time, saiddriving connection including disconnecting clutch means, electromagneticmeans energized when the motor is energized for operating said clutchmeans to complete said driving connection, resilient means effectivewhen the motor is deenergized to operate said clutch means to interruptsaid driving connection, a stop on the indicator side of the clutchmeans for stopping time indicating movement of said indicator after ithas been driven for a predetermined adiustable time, such stoppingaction and the continued operation of said motor causing clipping actionof the clutch means, an alarm operated by the electromagnet means inresponse to such slipping action and the continued operation of saidmotor and a spring which is wound when the indicator is driven forreturning the indicator to an initial position when the motor isdeenergized.

5. An alarm timer comprising a time graduated dial, an indicator movablewith respect to said dial and having an initial position with respect tosaid dial which is adjustable, a synchronous motor for' driving saidindicator over said dial from such initial position to indicate thepassage of time, stop means for stopping the movement of said indicatorafter it has been driven by said motor for a time corresponding to theposition of initial adjustment with respect to said dial, a drivingconnection between the motor and indicator which includes disconnectingclutch means, electromagnetic means energized and deenergized when themotor is energized and deenergized for operating said clutch means torespectively complete and interrupt said driving connection, a springbetween the clutch means and the indicator which is wound when theindicator is driven by the motor for returning the indicator to itsinitial position when the motor is deenergized, and an alarm operated byvibration of said electromagnetic means when said indicator is drivenagainst its stop and the motor remains energized.

6. A timer comprising a movable time indicator, a synchronous motor, adriving connection between said motor and indicator whereby the lattermay be driven by said motor at a constant speed to indicate the passageof time, said driving connection including a gear driven by the motor, agear for driving the indicator, a shaft, and a pair of intermediategears mounted on said shaft, one meshing with the motor driven gear andthe other meshing with the indicator driving gear, a pivoted frame onwhich said intermediate gears and their shaft are mounted which framemay swing between a position where said gears are in mesh to completethe driving connection to a position where the gear-train is interruptedat the motor driven gear, a spring connected with said indicator whichis wound up when the indicator is driven by said motor for returningsaid indicator to an initial position when the driving connection isinterrupted, a projection on the indicator driving gear which is rotatedinto contact with its intermeshing gear on said frame as a stop fordetermining the initial position of said indicator, said stopping actionbeing in a direction to urge the pivoted frame towards its gear-traininterrupting position, and means responsive to the energization anddeenergization of said motor for moving said frame to respectivelycomplete and interrupt said driving connection.

7. An alarm timer comprising an indicator, a synchronous motor having anexposed magnetic field structure, a drive-connection between said motorand indicator for driving the latter at a constant rate to indicate thepassage of time, said driving connection including a gear-train, a frameon which a portion of said gear-train is carried, said frame beingpivoted for limited movement, a magnetic armature. connected to saidframe and being positioned to be attracted to the field structure ofsaid motor when the latter is energized, a stop for stopping the timeindicating movement of said indicator after it has been driven by themotor for a predetermined time interval, said stopping action and thecontinued operation of said motor serving to cause relative movement ofsaid frame and a retraction of the magnetic armature from its attractedposition against the field structure to a position where the armature iscaused to vibrate under the influence of the alternating flux of saidfield and set up an audible sound which continues until the motor isdeenergized.

HENRY E. WARREN.

